Phytosterols and their esters possess hypocholesterolaemic properties, i.e. these substances are capable of lowering the cholesterol level in the blood. Accordingly, they are used as food additives, for example for the production of margarine, frying oils, sausage, ice cream and the like. The production of sterols and other unsaponifiable constituents, such as tocopherols for example, from distillates obtained in the deacidification of vegetable oils, has already been variously described in the literature, cf. EP-A2 0 610 742 (Hoffmann-LaRoche), GB-A1 U.S. Pat. No. 2,145,079 (Nisshin Oil Mills Japan) and EP-A1 0 333 472 (Palm Oil Research and Development Board).
European Patent EP-B1 0 656 894 (Henkel) describes a process for the production of sterols in which a residue from the distillation of methyl esters consisting essentially of glycerides, sterols, sterol esters and tocopherols is transesterified with methanol in the presence of alkaline catalysts. After neutralization of the catalyst, removal of the excess methanol by distillation and, optionally, removal of the catalyst by washing, the sterols are crystallized by lowering the reaction temperature from about 65 to 20° C. The crystals obtained are then washed with methanol and water. However, where residues from the production of methyl esters based on sunflower oil are used, the sterols obtained contain not only the target components, such as above all campesterol, campestanol, stigmasterol, β-sitosterol and β-sitostanol, but also significant amounts of citrostadienol which is undesirable for applicational reasons. German patent application DE-A1 3226225 (Raisio) describes a process by which the amount of citrostadienol can be reduced. In this process, the solid sterols are first dissolved in heptane and then re-crystallized after addition of methanol. However, the resulting products are by no means free from citrostadienol and, in addition, the yields are unsatisfactory.
Accordingly, the problem addressed by the present invention was to provide high yields of phytosterols which would be distinguished above all by the fact that they would be largely free from citrostadienol.